• Myasthenia Graves (MG) is an autoimmune disorder wherein antibodies attack acetylcholine nicotinic postsynaptic receptors at the myoneural junction, resulting in muscle fatigue (commonly bulbar) that worsens with use and improves with rest.  MG flares are most commonly due to infection or inadequate treatment with cholinesterase inhibitors.

• The Tensilon (edrophonium) challenge test can be used to help distinguish an MG crisis from a cholingergic crisis.  Once the airway and ventilation are secure, escalating doses of edrophonium (i.e. 1 mg, then 3 mg, then 5 mg, up to a maximum of 10 mg total) can be administered with the goal of relieving the muscle weakness.  If a true MG crisis is present, patients usually respond with dramatic improvement within 1 minute.  Patients having a cholinergic crisis, on the other hand, typically respond with increased salivation, bronchopulmonary secretions, diaphoresis, and gastric motility.  

• Monitor closely as edrophonium can cause significant bradycardia, heart block, and asystole (only 0.16% risk by reports, but have atropine nearby). 

• Once the edrophonium wears off, patients having an MG crisis may develop increased secretions and respiratory distress as their muscle weakness returns, so manage expectantly and with caution.  

Show References

Hypertensive Emergency Pearls

• Recent literature indicates that many patients with a true hypertensive emergency are mismanaged.
• Patients with a hypertensive emergency should have an arterial line placed and receive a continuous infusion of a short-acting, titratable medication to reduce blood pressure.  Avoid oral, sublingual, and intermittent IV bolus administration of antihypertensives. 
• Recall that most patients with a hypertensive emergency are volume depleted.  Providing IV fluids can help to prevent marked drops blood pressure when you start an IV antihypertensive medication.
• Avoid diuretics (due to volume depletion) and hydralazine.  Hydralazine can cause precipitous drops in blood pressure and is felt by many to have no role in the treatment of hypertensive emergencies.

Show References

The 30-day mortality for patients < 65 years of age who are diagnosed with and treated for acute MI is 3%. In contrast, the 30-day mortality for patients > 85 years of age who are diagnosed with and treated for acute MI is 30%! Obviously the mortality is far higher if the patient's diagnosis is delayed or missed; or if the patient is not treated appropriately.

This simple statistic highlights the critical importance of being aggressive with diagnostic and therapeutic planning for elder patients with potential ACS. We cannot afford to be cavalier in their evaluation or treatment.

Show References

Arthrocentesis of the Wrist

First locate and feel comfortable identifying two important landmarks:

1) Lister's tubercle is an elevation found in the center of the dorsal aspect of the distal end of the radius

http://www.aafp.org/afp/2004/0415/afp20040415p1941-f2.jpg

2) The extensor pollicis longus (EPL) tendon runs in a grove just radially to Lister's tubercle. Active extension of wrist and thumb aid with identification.

http://www.rad.washington.edu/academics/academic-sections/msk/muscle-atlas/upper-body/extensor-pollicis-longus/atlasImage

A) Positioning:  Place wrist in ulnar deviation and 20 - 30 degrees of flexion. Apply longitudinal traction to the fingers of the hand.

B) Technique:  Insert a small needle (22g) just distal to the tubercle and on the ulnar side of the EPL tendon.

http://img.medscape.com/pi/emed/ckb/clinical_procedures/79926-79928-80032-1477044tn.jpg

http://www.youtube.com/watch?v=nlPdb_mymw4&feature=related

http://www.youtube.com/watch?v=UVG7fZvZD-s&feature=related

Show References

• ocurs with significant lateral traction during vaginal delivery of an infant
• results in damage to the upper part of the brachial plexus, especially the 5th and 6th cervical roots
• results in paralysis of hte shoulder and arm
• the affected arm is held in adduction and internal rotation
• most resolve spontaneoulsy, but some may require physical therapy after 2 weeks
• surgery is rarely required, and has poor results
• always palpate for ipsilateral clavicel fractures!

Show References

Several medications have been linked to causing idiopathic intracranial hypertension (pseudotumor cerebri). Be sure to record an accurate medication history in patients you suspect of having this diagnosis.

• Excessive doses of vitamin A
  • Other retinoids too: retinol, isotretinoin, and tretinoin
• Tetracyclines (tetracycline, doxycycline, minocycline)
• Growth hormone

Withdrawal of the offending agent will generally resolve the symptoms.

• Remember that lithium overdoses should not be treated with oral activated charcoal, as these charged particles are not adequately absorbed by this method.
• Instead, whole bowel irrigation using 500 mL to 2 liters of polyethylene glycol should be administered within the first 2-3 hours of presumed large ingestions (ie. at least 10 to 15 pills), with a goal of having the patient pass stool to the point of clear rectal effluent.
• Hemodialysis (HD) should be reserved to treat severe lithium toxicity, which is somewhat loosely defined as a serum level greater than 3.5 to 4 meq/L (mmol/L). 
• For levels > 4 meq/L, most experts agree that HD should be performed regardless of whether associated symptoms are present.  For levels > 2.5 meq/L with associated clinical signs/symptoms (i.e. tremulousness, dizziness, lethargy, seizure), conditions that would limit lithium excretion (i.e. renal insufficiency), or conditions that would limit ability to aggressively hydrate (i.e. CHF), HD should be performed.   

Show References

Positive-pressure ventilation (e.g., mechanical ventilation) increases intrathoracic pressure potentially reducing venous return, right-ventricular filling, and cardiac output.

Pericardial tamponade similarly causes hemodynamic compromise through increased pericardial pressure which reduces right-ventricular filling and cardiac output.

When mechanically ventilating a patient with known or suspected pericardial tamponade the mechanisms above may be additive, causing cardiovascular collapse and possibly PEA arrest.

For the patient with known or suspected pericardial tamponade consider draining the pericardial effusion prior to intubation or delaying intubation until absolutely necessary.

If intubation is unavoidable, consider maintaining the intrathoracic pressure as low as possible (by keeping the PEEP and tidal volumes to a minimum) to ensure adequate cardiac filling and cardiac output.

Show References

Blood pressure cuffs tend to OVERESTIMATE true blood pressure in obese patients. Even larger cuffs tend to do this as well. While low blood pressures are often reliable in diagnosing shock, be wary of  assuming a "normal" blood pressure (e.g. SBP 100-120s) rules out shock in an obese patient who is sick. A-lines might be necessary to accurately assess the blood pressure.

[adapted from ACEP talk by Dr. Tiffany Osborn]

A recent randomized trial compared nicardipine as a continuous infusion to labetalol boluses to determine which one was more effective at lowering blood pressure to a target range within 30 minutes.

Median initial SBP for the 226 patients was 212 mm Hg. Within 30 minutes, nicardipine patients more often reached target range than labetalol (91.7 vs. 82.5%, P = 0.039). Of 6 BP measures (taken every 5 minutes) during the study period, nicardipine patients had higher rates of five and six instances within target range than labetalol (47.3% vs. 32.8%, P = 0.026).

What this means: Nicardipine is a reasonable choice for patients needing acute lowering of blood pressure (e.g., ischemic stroke with tPa).  Nicardipine seems to achieve faster and smoother lowering of blood pressure than labetalol therapy with less blood pressure readings outside the target range.

Show References

Salicylates:

• stimulate the respiratory center in the brainstem, causing respiratory alkalosis
• interfere with the Krebs cycle, limiting ATP production, leading to an anaerobic metabolism
• uncouple oxidative phosphorylation, causing accumulation of pyruvic and lactic acid and heat production, resulting in acidosis and hyperthermia
• increase fatty acid metabolism, generating ketone bodies

Overall, this results in a mixed respiratory alkalosis and metabolic acidosis. 

Show References

• A huge limitation to effectively managing acute ischemic stroke in rural areas is the frequent lack of access to local experts in vascular neurology.  While most guidelines encourage the use of telemedicine to overcome such barriers, the start up costs of such programs are sometimes prohibitive, particularly for small, rural practices. 
• A recent, small study showed that providers may be able to use the iPhone as a primary or adjunctive tool with telemedicine, to properly diagnose and manage acute stroke.
• The study compared a face-to-face provider's NIH Stroke Scale (NIHSS) interpretation to that of a remote provider using an iPhone with FaceTime software that allows real-time streaming of audio and video.
• Agreement between providers was excellent (intraclass correlation coefficient 0.98); the NIHSS score of the providers did not differ by more than 1 point in 17 of the 20 cases; in only one category - ataxia - was agreement poor.
• TAKE HOME POINT:  Streaming real-time video technology may offer an effective and economically feasible alternative to suboptimal acute stroke care in rural areas or an alternative/adjunct to pure telemedicine programs.  (This is not an advertisement or endorsement for the iPhone.)

Show References

Mechanical Ventilation in Patients with Pulmonary HTN 

• In the critically ill patient with pulmonary HTN and respiratory failure, improper mechanical ventilator settings can be disastrous.
• Large lung volumes and high levels of PEEP can result in acute cardiovascular collapse.
• When setting the ventilator is these patients, select low tidal volumes and relatively low levels of PEEP (3-5 cm H₂O).
• In addition, small studies suggest avoiding permissive hypercapnia, as this may increase pulmonary vascular resistance and mean pulmonary arterial pressure.

Show References

Question

72 year-old man, one-week post right fem-pop bypass presents with painful blue and black toe. Diagnosis?

Show Answer

Show References

Today's cardiology pearl provided by EMS guru Dr. Ben Lawner. Consider this one if you are caring for a patient with what appears to be shock-resistant VFib.

An intervention that has its roots in the electrophysiology lab has now gained traction on the front lines of resuscitation: double sequential defibrillation. Prospective studies are currently underway to examine the feasibility of this technique. New Orleans (LA) EMS boasts several anectodal accounts of survival, with neurologically intact recovery, from refractory ventricular fibrillation. The next time you can’t stop the fibbing, consider this:

·       Apply TWO sets of defibrillator pads to the patient; one in traditional sternum/apex configuration and the other in anterior/posterior configuration

·       If ventricular fibrillation persists despite several shocks, coordinate the simultaneous firing of BOTH defibrillators

Some caveats:
This treatment is based upon EP lab data; each MONOPHASIC defibrillator was set at 360J. EMS services in New Orleans and Wake County (NC) have used two biphasic defibrillators, each set a 200J. There is not sufficient data to make any widespread recommendation, but the idea of double sequential defibrillation may be another tool in a limited ACLS bag of tricks for patients who simply cannot come out of V-fib. New Orleans EMS has initiated the double-defib protocol after four shocks, and Wake County’s protocol recommends initiation after five. Wake's protocol also recommends firing the defirbillators "as synchronously as possible."

Show References

Methotrexate is a chemotherapeutic that is utilized in non-Hodgkin lymphoma and breast CA. It is also used as an immunosuppressant for rheumatoid arthritis and psoriasis. Finally, we see it used in the ED for the treatment of ectopic pregnancy. Overdose, often unintentional, can have a lethal outcome.

Toxicity: LFTs rise, N/V, stomatitis, mucositis, leukopenia, thrombocytopenia, renal failure

Antidote: Leukovorin (Folinic Acid)

Other Tx: Carboxypeptidase G2, Charcoal Hemoperfusion, HD (possible)

• Myasthenia Graves (MG) is often associated with several, distinct clinical findings which patients may have during their crisis in the emergency department. These findings may include the following:

              -  Mask-like face

              -  Eyelid weakness 

                    --  leads to ptosis

                    --  exacerbated by sustained upward gaze

                    --  improved by closing the eyes for a short while

                -   Extraocular motion abnormality

                     --  usually affects more than one extraocular muscle

                     --  may be assymetrical

                     --  may result in mild proptosis

                 -   Weak palatal muscles

                      --  nasal-sounding voice

                      --  nasal regurgitation of food

                  -  Weak jaw muscles

                  -  Absent gag reflex

                  -  Pupils normal

• On October 25, 2011, Eli Lilly announced a voluntary-recall of activated drotrecogin alfa (Xigris) following a recent trial (PROWESS-SHOCK), which demonstrated no survival benefit when using the drug when compared to placebo.

• Activated drotrecogin alfa is a recombinant form of human activated protein C previously recommended for adults with severe sepsis and a high-risk of death (APACHE II > 25 or multi-organ failure); it is included in the 2008 International Sepsis Guidelines (Grade 2b recommendation).

• The PROWESS-SHOCK trial reported an all-cause mortality rate of 26.4% in the drotrecogin alfa group compared with 24.2% in the placebo group; this difference was not statistically significant.

• Interestingly, the study also found that severe bleeding (the drug's main side-effect) was found to be 1.2% in the activated drotrecogin alfa group compared to 1.0% for the placebo group (also non-significant) suggesting it does not increase the risk of bleeding as it had previously been reported.

• Hospitals should revise their sepsis guidelines based on this recent news.

Show References

Weird and Unusual Symptoms

Bet you didn't know that severe and intense pruritus of the nostrils, known as Wartenberg's symptom, is an uncommon but characteristic symptom of a brain tumor.

Etiologies include astrocytoma, glioblastoma, oligodendroglioma, medulloblastoma, and metastatic tumors.

Show References

"Women experience higher mortality rates and more adverse outcomes after acute MI than men, despite less obstructive CAD and plaque burden."(1)

How can this be explained? It turns out that women have more frequent coronary remodeling of vessels. "Remodeling" refers to the concept that as plaques grow, they tend grow into the vessel wall causing outward bulging of the wall, rather than growing into the vessel lumen. That means that standard coronary angiography and even stress testing often miss significant lesions because they only evaluate lumen obstruction....which is not directly reflective of plaque size/burden.

The net effect of the above is that women are more likely to have false negative stress tests and angiograms that appear to show non-significant occlusions. Until we have reliable tests that evaluate true plaque burden rather than just vessel occlusion, we can't completely rely on stress testing and angiography to rule out the the presence of significant plaques.

Show References